1. Field of the Invention
The present invention relates to a power distributing box for an automobile and a power-device module which is useful for the power distributing box.
2. Description of Related Art
Generally, an automotive power distributing box has a casing, a bus-bar connected to a power source (battery), a plurality of bus-bars having respective terminals connected to respective loads, a plurality of power devices interposed between the bus-bar on the side of the power source and the bus-bars on the side of the loads to control the power supply to the loads and a circuit baseplate having a built-in driver circuit for transmitting control signals to the power devices.
In the prior art power distributing box, it is general that package components are employed for the power devices. The package components are installed on the circuit baseplate. Respective terminals of the power devices are soldered to circuit conductors on the circuit baseplate. Further, the bus-bars are connected to respective terminals of the power devices and the circuit baseplate by connecting means, for example, connectors, jumpers, etc.
In this way, the conventional power distributing box is required to employ the above connecting means, such as connector and jumpers, for connecting the terminals of the power devices and the circuit baseplate with the bus-bars. Consequently, a number of components are required for the conventional power distributing box, causing its manufacturing cost and a space necessary for the box to be increased.
Under such a situation, it is therefore an object of the present invention to provide a power distributing box which enables reduction of both manufacturing cost and space due to the reduced number of components, and also provide a power-device module for realizing such a power distributing box.
The above-mentioned object can be solved by providing a power distributing box electrically interposed between a power source and respective electrical loads, the power distributing box comprising:
a casing;
a power-source side bus-bar accommodated in the casing and connected to the power source;
a plurality of load side bus-bars accommodated in the casing, the load side bus-bars having respective terminals connected to the electrical loads respectively;
a plurality of power devices accommodated in the casing and respectively interposed between the power-source side bus-bar and the load side bus-bars to control power supply for the electrical loads; and
a circuit baseplate accommodated in the casing to have a built-in driver circuit for transmitting control signals to the power devices;
wherein the power devices in the form of bare tips are arranged on and connected to either one of the power-source side bus-bar and the load side bus-bars; and the power devices are connected to the circuit baseplate and the other one of the power-source side bus-bar and the load side bus-bars, through wire bondings.
According to the power distributing box constructed above, the power devices in the form of bare tips are arranged on and connected to either one of the power-source side bus-bar and the load side bus-bars. Further, the connection between the power devices and the circuit baseplate and the connection between the power devices and the other one of the power-source side bus-bar and the load side bus-bars are accomplished by the wire bondings. Therefore, there is no need to use means for connecting the elements with each other (e.g. connectors, jumper lines, etc.). That is, since the above-mentioned structure is different from the conventional structure where the circuit baseplate is equipped with package components, it is possible to reduce the number of components.
Further, owing to the arrangement where the bus-bars (i.e. the power-source side bus-bar or the load side bus-bars) are respectively equipped with the power devices in the form of bare tips, there is no need to secure the installation space of the power devices on the circuit baseplate and also no need to spread power lines on the circuit baseplate. Therefore, due to the miniaturization of the circuit baseplate, it is possible to reduce the size of a space occupied by the power distributing box.
As the second aspect of the invention, each of the terminals of the load side bus-bars is shaped so as to be a tuning fork having a slit allowing an insertion of a plate-shaped terminal of a fuse.
Owing to the above formation of the terminal, it becomes possible to fit a terminal of a fuse to the tuning-fork type terminal directly.
As the third aspect of the invention, an installation area of the power devices and a connecting area of the wire bondings are covered with a resinous mold. Consequently, it is possible to provide the power distributing box resistant to an external shock.
As the fourth aspect of the invention, the power distributing box of the first aspect further comprises a radiator plate for mounting the power-source side bus-bar and the load side bus-bars thereon, wherein the radiator plate having the power-source side bus-bar and the load side bus-bars thereon is accommodated in the casing.
In this case, since the radiator plate mounting the power-source side bus-bar and the load side bus-bars thereon is accommodated in the casing, it becomes possible to assemble the power distributing box with ease and also possible to enhance the heat-radiation from the power devices.
As the fifth aspect of the invention, there is also provided a power device module to be electrically interposed between a power source and respective electrical loads, the power device module comprising:
a power-source side bus-bar connected to the power source;
a plurality of load side bus-bars having respective terminals connected to the electrical loads respectively;
a plurality of power devices respectively interposed between the power-source side bus-bar and the load side bus-bars to control power supply for the electrical loads;
a plurality of connecting terminals connected to the power devices, for transmitting control signals to the power devices; and
a resinous mold for covering the power-source side bus-bar, the load side bus-bars, the power devices and the connecting terminals, in integration; wherein the power devices in the form of bare tips are arranged on and connected to either one of the power-source side bus-bar and the load side bus-bars; and the power devices are connected to the connecting terminals and the other one of the power-source side bus-bar and the load side bus-bars, through wire bondings.
According to the above-mentioned structure of the power device module, if only mounting this power device module on a circuit baseplate as a constituent of the power distributing box and further connecting the connecting terminals with circuit conductors on the circuit baseplate, then it becomes possible to finish the power distributing box with ease.
Accordingly, since it is unnecessary to prepare connecting means (e.g. connectors, jumper wires) in order to establish the connection between the circuit board and the power devices and also the connection between these bus-bars (i.e. the power-source side bus-bar, the load side bus-bars) and the circuit board, it is possible to reduce the number of components forming the power distributing box. Additionally, as these bus-bars and the power devices both indispensable to the power distributing box are installed in the power device module, there is no need to provide superfluous bus-bars besides the module 60 and additionally, power lines wired in the circuit baseplate are eliminated. Therefore, it is possible to reduce an occupation space necessary for the installation of components. Since the plural power devices are in the form of bare tips and the individual power device and the corresponding load side bus-bar are gathered just like a single component, it is possible to reduce a space occupied by the components in comparison with a case that discrete components of the same number are arranged.
As the sixth aspect of the invention, in the power device module, the load side bus-bars are arranged on one side of the power-source side bus-bar at intervals of a first pitch each. The connecting terminals are arranged on the other side of the power-source side bus-bar at intervals of a second pitch each, the second pitch being smaller than the first pitch thereby defining at least one free space at the end of the array of the connecting terminals. The power device module has an attaching part established in the free space, for attachment of the power device module.
Therefore, by putting the free space in effective use, it is possible to provide the small-sized power device module.
As the seventh aspect of the invention, in the power device module, the load side bus-bars are arranged on one side of the power-source side bus-bar at intervals of a first pitch each. The power device in the form of bare tips are arranged on the power-source side bus-bar at intervals of a third pitch each, the third pitch being smaller than the first pitch thereby defining at least one free space at the end of the array of the power devices. The power device module has a connecting part established in the free space, for external connection of the power-source side bus-bar.
Also, by putting the free space in effective use, it is possible to provide the small-sized power device module.
As the eighth aspect of the invention, in the power device module, each of the terminals of the load side bus-bars is shaped so as to be a tuning fork having a slit allowing an insertion of a plate-shaped terminal of a fuse.
Also in the power device module, owing to the above formation of the terminal, it becomes possible to fit a terminal of a fuse to the xe2x80x9ctuning-forkxe2x80x9d type terminal directly.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompany drawing.